Weakness
by ShannieP
Summary: All teams have weaknesses. STRIKE Team Delta only had one, and it cost them more than they'd like to admit. Possible Clint/OC
1. Chapter 1

*Rated M for possible future content. There will most likely be strong language, violence and sexual content ~S

* * *

 _ **Weakness: Chapter 1**_

 _'That' Mission_

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Every well-seasoned agent of SHIELD had 'that' mission. That one mission that completely and utterly destroyed their lives forever. Nairobi, Amsterdam, Kiev, Shanghai. For some, it was a mission gone south. Maybe a partner died, or a mentor, or a handler. Maybe they'd been captured; maybe they'd been tortured. Maybe they blew up an entire apartment complex packed with innocent civilians just to eliminate their one target.

For others, it was the complete opposite. A mission gone so perfectly, so cleanly, that they began to question even their own morality. A mission that made them question what exactly it meant about them that they could kill someone so flawlessly, so effortlessly, without a hint of hesitation or conscience or doubt. Maybe the target reminded them of someone – their daughter, their brother, their uncle. Maybe the target seemed innocent – maybe it was a child, a mother, a veteran. Maybe years ago you fought on the same side.

No one knew when their 'that' mission would appear. For some, it came right away. Their very first steps into this new life, barely out of training, and they were shot down and subdued like an animal in a cage. For most, it came after a few years, when they were least expecting it: when they'd grown comfortable, when they'd grown cocky, when the universe decided they needed putting in their place.

But no one escaped it. And no one forgot.

Sometimes an agent shared 'that' mission with other agents. Perhaps it was 'that' mission for an entire STRIKE team. Occasionally entire squadrons were rendered compromised for years to come by the same single operation. Other times an agent had their own personal 'that' mission. Maybe it had been a solo mission, or maybe no one else was affected in the same way. It didn't matter: either way they were left alone to grasp at the shambles that once was their life, with no hope of ever putting it back together.

There was no returning from 'that' mission. No way for an agent to revert back to the person they were before. For most, it marked the beginning of the end. Honourable discharge followed by a downward spiral of self-hate and destruction. The nightmares were the worst, and no amount of therapy or medications could stop them from following. Support groups were made, hoping to reach out to ex-agents who understood what they were going through. It soon became apparent that no one would ever relate, because they weren't there, and they hadn't lived your life. Maybe they could sympathise, or offer an ear to listen, but they'd never understand.

There were very few who returned to active duty after 'that' mission. Even fewer that came back after a second. And a third. And a fourth. But they existed, so the rumours said. Maria Hill still stood at Fury's side even after Steckborn and Bavaria. The Cavalry returned after Manama, and even Phil Coulson himself had returned after, what the stories say was, a blood bath in Košice. They never recovered, but they persevered. It made them stronger.

And then there was, of course, STRIKE Team Delta – a whole league of their own. Abidjan, Kinshasa, Cairo, Havana, Warsaw. These were only a handful of operations that sprang to mind when talking about STRIKE Team Delta. It's what made them the best. Some believed even untouchable. How wrong they were.

Clint Barton, Natasha Romanoff and Alexandra Denton. Three of the world's most deadly assassins. Skillsets too vast and too broad to list; too many to count. And only one weakness. Each other.


	2. Chapter 2

*Not really sure where this story is heading. We'll find out, I suppose ~S

* * *

 _ **Weakness: Chapter 2**_

 _Missing_

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Something wasn't right. Tony had caught onto it almost right away. Steve had taken a while longer to catch on, but eventually he began to notice the tension in the room too. Sam had complained it was bringing him down before leaving. Even Pepper noticed, and she had only come in to grab some food before promptly leaving. Something was wrong. They could read it in the way Clint slouched in the couch opposite the door, staring, unseeing and wearing the same clothes as the day before, wrinkled as if he'd tried to sleep in them and failed. They could see it in the way Natasha sat on the floor in front of him, back rested against his knees, eyes never leaving the phone in her hands, typing furiously every time a message alert went off. Every so often the phone rang as someone called, and every time an angry conversation in Russian would ensue. Most times, the phone ended up ripped from Natasha's grip as Clint intruded on the conversation.

They'd tried to help. Steve had already approached them twice and asked what was wrong. Both times all he'd gotten in response was a blank stare from Clint and a muttered 'Classified' from Natasha. Tony had tried to approach it in a different way, and had went to swipe the phone from Natasha's hand. He ended up on his back on the coffee table before he could so much as lay a hand on it, Clint's knee digging into his chest with an instruction to 'Mind your own business, Stark.' The closest they got to understanding was when Bucky had returned from his evening run, only to overhear one of the many heated Russian conversations between Natasha and whomever was on the other end.

"Who's missing?" He'd asked Steve, who only looked at him blankly in return. Tony suddenly perked up and made his way over to the two super soldiers, hoping someone could _finally_ shed some light on the matter. Before Bucky had returned, he'd been tempted to start learning Russian just so he could _maybe_ understand what the hell was going on.

"Missing?" Bucky nodded, making his way over to the kitchen to make himself coffee, feeling like he was intruding on the conversation that the two assassins obviously didn't want people listening into. The two men followed him quietly, trying to ignore it as Natasha got louder and Clint suddenly joined in too.

"Natasha was asking if they had found anything that may help find her." The two voices were just getting louder, and Bucky couldn't help but overhear. Maybe he could help? They seemed pretty desperate, and in the few months that he'd lived with the assassins, they'd become close friends. They were the closest it came to understanding what he had been through. He wanted to help. "Clint wants to go look for her."

"Her?" It was Tony who had asked, but Steve wanted to know too. Bucky just shrugged, unsure, grabbing his newly made coffee and making his way back to the lounge, where the voices had quietened to hisses and Clint had commandeered the phone. After a few final muttered words, which Bucky thought sounded suspiciously like 'Get her home, or else I've got an arrow with your name on it right here', he hung up and threw the phone back down to Natasha who just nodded and closed her eyes, obviously exhausted. Tony opened his mouth to say something but suddenly JARVIS spoke up,

"Agent Barton?" The man in question looked up to the ceiling, obviously irritated at the system, not wanting to talk. His eyes were glassy and not quite in the present, so Natasha spoke up for him.

"What is it, JARVIS?"

"There's a woman in Agent Barton's room, Agent Romanoff." The two assassins were on their feet in seconds, as everyone looked around the room in shock.

"What? Barton did you bring a god damn booty call back here with you? I didn't know you had it in you!" Tony laughed, going silent when the man in question shot him a glare.

"How did she get in?"

"She entered through a window on the top floor, Agent Barton, but her biometrics are in my database." Clint and Natasha shot each other looks, knowing only one person who would enter through a top floor window and sneak into one of their rooms rather than use a perfectly functioning elevator. And only one reason why that person might do it. Suddenly they both shot off, making for his room, leaving Tony, Steve and Bucky to trail after them, more confused than ever.

When the trio reached Clint's room the door was swung wide open, leaving them able to peak into the assassin's room – not daring to enter. Sure enough there, lying face down on the bed, was a woman none of the three could identify. One hand was wrapped in the pillow above her head, the other was wrapped in Natasha's, who sat on the bed next to her. Clint kneeled by the bed, next to her head, one hand on top of the mysterious woman's head, stroking down the blonde hair. His eyes were everywhere, running down the entirety of her body, searching. For what, the trio didn't know. Steve and Bucky shifted uncomfortably, gathering the sense that they were intruding on what seemed to be a very private moment. Tony, however, stared.

"Who is this and what's she doing here, Barton?" Everyone in the room ignored him, and Clint's appraisal continued until his eyes landed on the back of her head and stilled. The two super soldiers took it upon themselves to leave now, confident that the assassins would explain later when they were ready. When whatever _this_ was had been taken care of. Tony remained.

"Ali, what are you doing here?" It was the first word spoken, and the woman on the bed shifted, grunting.

"Finished m' mission." Eyebrows raised, Tony took a second to appraise the girl. Ignoring the fact that she was currently face down on Barton's bed, she definitely fit the SHIELD agent vibe. All black clothes, giant military-grade boots on her feet, and from what he could see, distinctively muscular. He could see a holster on the ground next to the bed – nope, make that two. Definitely SHIELD. Well, ex-SHIELD. SHIELD itself had been disbanded after the whole HYDRA fiasco, but technically it still ran. People loyal to Fury and Hill still ran missions, still took operations and launched attacks for them. Technically they worked under the Avengers, but he knew he had never met this woman.

"You've been missing five days." It suddenly hit Tony that this was the woman that was missing – the woman that had caused the depressing mood the two spies had been in all day. The state she was in, the grime that covered every inch of her that he could see, definitely suggested she'd been MIA and hadn't had access to a bathroom in a while.

"…Hit a bump." Clint snorted, rolling his eyes, a small grin appearing on his face before it disappeared in an instant, obviously remembering something. His eyes ran a trail down her body again, stopping around her stomach.

"Are you bleeding on my bed?" The woman, Ali, groaned, as if only just remembering and twitched slightly, nodding into the pillow.

"Yep." Natasha was off the bed and in front of Tony in an instant, an unapologetic grin on her face before she slammed the door shut and turned the lock, effectively shutting Tony out, who groaned and banged on the door, his last sight being Clint wrapping one arm around the blonde and starting to help her off of the bed, and a deep red stain on the sheets below her.

"C'mon Romanoff, this is technically my building! I should know what's going on at least!"

"Not now, Stark!" Was the only answer he got, and he finally sauntered off, looking up at the ceiling before calling out.

"JARVIS, who is that?" The AI responded with only four words.

"No information available, sir."


	3. Chapter 3

*Some mild swearing ~S

* * *

 _ **Weakness: Chapter 3**_

 _Routine_

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"Alright, easy Ali." Clint muttered, one armed wrapped around the woman's waist, another holding her arm in a tight grip in an attempt to keep her upright. She'd lost a lot of blood, if the amount currently staining his bed sheets was anything to go by. "We'll get you fixed up real quick, kid." As the two slowly made their way to the bathroom, Natasha puttered around inside, knowing exactly where everything she needed was. If you'd been in one SHIELD agent's room, you'd been in them all. It didn't hurt that this was certainly not the first time she'd been in this situation, though admittedly it was usually Clint being dragged across the room.

"So what we got?" Natasha asked as Clint finally lifted Ali up onto the counter beside her. It was how it always was – one of them bleeding out on the counter, one acting as support, one playing doctor. Everything always slipped back into routine.

"Some fucker got lucky with a knife, three inches, nothin' original. I'd reckon a guess that it's bleedin' more than it's hurtin'." Natasha doubted that, but said nothing as she continued to gather what she needed.

"Up or down?" Ali grunted at Clint's question, squirming slightly on the counter as she considered the question. Both ways it would hurt, and both ways she'd rather avoid.

"Just cut it." Clint had been expecting that answer, and had already silently produced a knife from his pocket, cutting her shirt away from her body, and carefully pealing it from the gaping wound. The three fell into silence as Natasha worked, Ali not flinching as the alcohol stung at her flesh. This was routine. It had happened more times than she could remember – it was comforting, in a way. Clint's eyes had gone back to surveying Ali's body, her newly exposed torso now under his scrutinising gaze. There were several more cuts and bruises littered across her body, one particularly nasty purple bruise around her throat which was distinctively in the shape of a hand. All-in-all it wasn't the worst shape he'd ever seen her in.

"Any more underneath?" He nodded at the trousers, and Ali shrugged as best as she could until Natasha scolded her, using one arm to hold down her hips and still the woman, the other hand still working away at the mutilated flesh.

"Nothin' much, some cuts, bruises – pretty standard." She seemed to think for a moment. "I think m' head's cut up. Guy thought it'd be fun to smash it into the wall." Clint nodded – he'd already noticed the dried blood clinging to one side of her face. It accounted in for her somewhat slurred speech too. A concussion seemed likely; they'd have to keep an eye on her that night.

Twenty minutes later found Ali blacked out on her back in Clint's bed, new sheets beneath her and one of his old shirts covering her torso. Clint was currently in the closet, dragging out the old mattress that forever lived in there. He'd changed into pyjama trousers after he'd managed to get the unconscious Ali settled on the bed. Natasha had left to call Hill and report Ali safe, but soon re-entered in night clothes as Clint dropped the mattress directly next to his bed, shooting Natasha a quick look as she entered. "You've got the bed this time, Tasha." The woman just scoffed.

"Stop being an idiot, Clint. C'mon." She'd already climbed into one side of the bed next to Ali, and Clint just shook his head, climbing into the other side. No matter how many times it happened, it always started the same. One of them would drag out the spare mattress, and then the other would call them an idiot and get them to share the bed with whichever one of them was currently passed out on top of it. It didn't matter if it were a single, double, king sized – they'd always make it work. None of them mentioned it, but the nightmares were a little easier to handle when they were together. After Warsaw, they'd shared the same bed for six months straight, and on and off for just under two years. They'd just got comfortable sleeping on their own again when Cairo happened. It was a rough few years after that. They didn't mention it much.

Few people knew about the assassins' sleeping habits. Coulson had known – before everything that happened in New York. The man had been their handler for their entire stretch as STRIKE team Delta. It hadn't taken him long to pick up on it – how they'd all go to the same room after a mission, how during the mission they slept cramped in one corner instead of spread out across whatever rundown desolate building was acting as their base of operations. He'd never mentioned the multiple times he'd seen one of them waking up screaming when they weren't together, or how they'd immediately calm when the other two joined them. With the things they'd seen, and the things they'd done, they deserved to find a little solace in each other.

So that night, like many nights before it, the trio fell asleep together, all content in the knowledge that they were safe, and together, and that's all that really mattered. They would worry about introducing Ali to the rest of the Avengers tomorrow – and explaining why they'd never met her before– but for now, at least, they could sleep peacefully with the comfort of knowing that no nightmares would plague them that night.


	4. Chapter 4

*This is a lot longer than usual, wow. Do people prefer longer chapters? ~S

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 _ **Weakness: Chapter 4**_

 _Introductions_

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Waking up was not something Alexandra Denton enjoyed. Waking up alone was something she enjoyed even less, and waking up alone with a note on the dresser telling her to 'get dressed and get ready to be grilled' was probably Ali's definition of a nightmare. All of this equated in the assassin taking her sweet time in Clint's shower, knowing that if she took long enough one of her bed buddies would barge in and force her to get ready. In her defence, the shower was about as high-tech as it got (Stark's doing, no doubt – that man was practically the epitome of wealth), and that coupled with her injury caused her to take longer than she would like admit to even get the shower running.

Sure enough, twenty minutes after Ali had actually finished washing, Natasha burst through the bathroom door with a change of clothes in hand, glaring at the blonde as best she could through the steamed glass of the shower, and Ali only grinned in return. The nakedness of the woman bothered neither of them – STRIKE team Delta had passed the point of modesty around each other years before. You didn't spend day-in, day-out with each other for too long before nakedness no longer seemed like a big deal. There were, after all, bigger things to worry about.

"Ali, c'mon. The team are waiting, and I will not hesitate to drag your ass out there, naked or not." Ali didn't doubt it, and left the shower willingly, quickly drying and changing into the clothes Natasha had grabbed for her. They'd obviously come from Natasha's drawers, but the boxers were definitely Clint's, and the undershirt was one she'd bought herself two years before. By this point in their friendship, the trio wore each other's clothes possibly more than they did their own. Clint's boxers were a favourite between the two women, and Ali's hoodies were a favourite between both Clint and Natasha. Natasha's sweatpants were practically heaven-sent, and whenever she bought a new pair they'd be gone more often than not. It helped that the trio often bought unisex clothes, and that both Natasha and Ali both wore clothes a few sizes too big for the rare occasion that they had a lazy day. Practically anyone who had met the trio had noticed the habit, but few were brave enough to point it out, especially as the Widow's eyes bore into them as soon as they went to bring it up. Coulson had noticed, and on the few occasions one of his own shirts or hoodies went missing and he spotted one of them wearing it a few days later, he didn't mention it. It was an unspoken rule between the team – no one brought it up, and no one asked why. They all just knew.

"Who am I meeting?" Ali couldn't help but ask as they finally left the bedroom and headed towards the communal area. Due to a series of long-term solo missions, Ali had yet to actually meet the team known as the Avengers – despite, in an official sense, being part of it. STRIKE team Delta had been the first approached to be part of the Avengers Initiative, and Fury had made it clear that when Ali returned she would join. She had also tailed Bruce Banner for several months on the lead up to the Initiative, and felt a great sense of protectiveness over the man. Last she'd heard, Banner had gone back into hiding.

"Stark, obviously. Steve and Bucky are here. Sam's out but you'll meet him later. The rest are at the new base." Ali nodded, almost relieved that she'd finally be able to meet the people that Natasha and Clint so often told her about. Of course, she'd read their files. It had been part of her job when she used to have down time between missions – helping evaluate possible Avengers Initiative members. It's why she had tailed Banner, and why she knew where to find each Avenger at a moment's notice.

She knew it might be a little while before she met the rest of the team, if they were at the new facility. She knew for sure that Peter, Wanda and Vision all lived in the rural facility, and Scott Pym often visited. She also knew that the rest of the Avengers would have to follow soon, so she didn't worry too much about how long it would be before meeting them. In that respect, all she had to worry about was not getting too comfortable here in the tower, otherwise she'd become distressed when it came time to leave.

"Sounds fun." Natasha knew she was lying. Ali didn't trust people – none of them did, really, but Ali particularly was exceptionally hard to win around. Ali hadn't met these people before, hadn't gone through the same things as Clint and her had with them. All she had was the two assassins' words that they were good people, and whilst Ali trusted her partners with her life, she liked to be the one to assess people she would be spending a lot of time with. Sure, she had assessed them before the Avengers Initiative, but that had been professionally. That had been making sure they could do their job well and effectively. This? This would be personally. She had to know if this person was someone she could trust to have her back – someone who she could put her life into the hands of with the knowledge they wouldn't let her down. For the first time in, well, ever, Natasha was hoping something came up soon – a mission the team would be called out on so they'd be forced to bond. Ali needed first-hand experience to trust someone, and formed bonds quickest under high-stress, high-intensity situations. It's why STRIKE team Delta had worked so well – each mission only made them stronger.

"They're good people, Ali. Trust me." The woman just grunted, falling silent as they turned the corner to the main room and caught sight of the three men in question, standing talking to Clint in the middle of the room. Her bright blue eyes quickly ran over the three men she didn't know, automatically assessing them, noting any weak spots she could see. It was a habit as instinctual as breathing, but it didn't stop her from berating herself mentally – these were meant to be her teammates, she shouldn't be analysing them like an enemy.

Bucky turned around first, his own training from HYDRA kicking in as his heightened senses alerted him to someone unfamiliar in the room. The other three men followed quickly, conversation halting and a grin lighting up Clint's face as he walked over to the two women, enveloping Ali quickly – and carefully – in a hug before pulling away, eyes trailing down her body automatically before nodding, apparently satisfied that she hadn't somehow come to any more injury whilst he'd been away. Tony cleared his throat in the background.

"So, Katniss, who's this? And why was she bleeding on your bed?" Steve and Bucky looked up, alarmed, having left before it was revealed the woman was injured.

"'She' is right here, y'know?" Ali mumbled, but otherwise motioned for Clint to carry out the introductions – he was easily the most social out of the three.

"This is Alexandra Denton, long-time SHIELD agent and the third member of STRIKE team Delta." Clint paused for a second before grinning, "So basically, mine and Tasha's partner." Another pause. "And technically, a member of the Avengers." There was a silence for a few moments before Tony seemed to work through this information.

"Well I, for one, call bullshit. Why have I never heard of her if she is meant to be one of us? And why does JARVIS know nothing about her?" He paused, almost as if just realising the woman in question was still in the room. "No offense sweetheart, I don't buy it." Ali just shrugged.

"Smart man." Clint shot her a look, one that clearly told her to be quiet, and she relented – just this once, though. Whilst technically she was on the team, she wasn't really, not yet at least. So this was their team, and she'd let them handle it – after all, she didn't want to come between her partners and their team. Clint and Natasha didn't trust many people, and so if they trusted this team then she would play nice – for them.

"Before New York Fury had thought it would be a good idea for one member of STRIKE team Delta to be at base at all times." It was Natasha who explained, having caught on to the silent conversation between Clint and Ali. "He needed one of us to be there in case anything happened. We'd known for a while something big was coming." And they had. Months prior to New York STRIKE team Delta were separated after a particularly lengthy mission in Prague – Natasha was sent to watch Tony Stark and Ali was sent on a solo mission in the Alps, leaving only Clint back at HQ. Ali returned and Clint was sent to New Mexico with Coulson, which ended up with Thor introducing Asgardians to Earth. Natasha and Clint both returned and Ali was sent on a long-term mission on a submarine in the Indian Ocean. Coulson and Natasha both went along to oversee the thawing of Steve Rogers, though Natasha soon returned. Ali returned and she was almost immediately sent back out to Trinidad. Soon after, New York happened. Even after New York, Ali was repeatedly sent out on solo missions: apparently the operation in Trinidad had unveiled a whole new web to a relatively newly-discovered terrorist organisation, and Ali was the only one who knew all the details, and so the best equipped to handle the job. The overall result was that Ali never actually met her new team – the Avengers.

"New York happened whilst Ali was on a mission, and she's been relatively busy since then. But that's classified." Clint chuckled to himself, as if he'd told some great secret that only he was privy to, before sobering. "Is that over then, now?" They hadn't had much time to chat between her showing up on his bed and now. She'd been injured and concussed, so relatively little had been said as Natasha cleaned her cuts, and she'd passed out before they'd even made it back into his room.

"Yeah, that's over." Clint and Natasha couldn't help but grin. This meant two things – one: that the mission was a success, and two: STRIKE team Delta were back together. The previously silent blond super soldier in front of the trio now decided to speak, seeing the conversation seem to get away from the introductions and towards something more private.

"Well then, it's a pleasure to meet you Ma'am. Looks like we're going to be teammates. I'm Steve Rogers." She shook the offered hand firmly, grinning up at him slightly.

"Yeah, Captain America right? Thought I recognised you from somewhere." She teased, dropping his hand. "Call me Ali."

"Alright, Ali. And this is my friend, Bucky." Her eyes danced over to the man in question, who had been silently staring at her for the entire conversation. She knew this man – and not just from his files. They had run into each other a few times over the years. Luckily – for him or for her, she couldn't say – they'd never been after the same target, and she'd never been after one of his people, so they had managed to pass each other by without too much of a fight. Admittedly there were a few more scars riddled across her body due to him, but she knew that if the super soldier could scar, and didn't heal ridiculously quickly, the same could be said for him due to her.

"Nice to meet you properly." She nodded, not offering her hand, having the distinct feeling he didn't want to touch a stranger. She knew the feeling, but she had managed to fight it down over the years. He would too, eventually.

"I know you." Was his only answer, and she nodded.

"Yup, no hard feelings though. I hear you've been taking care of these losers whilst I was away, so we're good in my books." She bumped her hips with Natasha's and Clint's as they stood either side of her, wincing slightly as pain shot through her and she remembered that she really shouldn't be moving like that. Natasha and Clint noticed immediately and led her over to one of the couches, forcing the other three men to follow as they sat either side of her. Tony obviously wasn't through with her.

"Okay, say I believe that you've been on missions all this time – which I don't, by the way. Why doesn't JARVIS know who you are?" Ali grinned, leaning back into Clint slightly and swinging her legs over Natasha's.

"I have a talent for computers and a thing for privacy. Sue me." Of course that wasn't the whole story, but sometime into the Trinidad situation it became imperative that all files on her were locked down – level 9 security required. When it became apparent that there was a leak within SHIELD, she deleted the files completely. The only files remaining showed her name, rank and team, along with a picture of her face for identification purposes. Her biometrics were saved, again for identification purposes, now under a level 10 security lock. All her missions and operations were gone – as if they never happened.

Tony seemed somewhat impressed, at the very least, and that would have to do for now. Ali looked around idly, taking in the room properly for the first time, before a loud noise from her stomach caused her to look over at the three men in front of her. "If you excuse me, I haven't eaten in four days and I'm starved." And then she turned to Clint, who was frowning at her admission. "Know any good breakfast places?" Clint opened his mouth, but it wasn't his voice that spoke up next.

"I do." All heads turned to Bucky, who himself looked shocked that he had spoken up. "I know a place. We could all go. If we're gonna be a team we should get to know you, right?" All the present Avengers murmured their agreements and in minutes they were out the door, arguing over which place was the best to 'take her New York breakfast virginity', as Tony called it. Clint and Natasha stuck by Ali's side, just like old times, and suddenly she felt at home.

Ali, admittedly, could get used to this.


End file.
